The goal of this study is to develop a robust and sensitive assay adaptable to high throughput screening of chemical libraries, which in turn would identify specific inhibitors of human peptide deformylase (HsPDF). Both the inhibition of HsPDF activity by actinonin, and the inhibition of HsPDF expression by RNA interference lead to proliferation arrest in a variety of tumor cell lines. HsPDF therefore constitutes a novel target for anticancer agents, and specific HsPDF inhibitors could constitute a new class of antitumor agents. For the purpose of identifying new inhibitors based on unique motifs not likely to interact non-specifically with proteases, we will proceed to the screening of a large library of 200,000 compounds. To achieve that goal, we plan to develop a high-throughput screening strategy based on two different assays. A primary screen will employ a novel fluorescence polarization assay to rapidly identify HsPDF binders, and a secondary screen based on a functional assay will be performed in order to select the best HsPDF inhibitors. The rationale behind this two-step screening strategy is to efficiently sort out compounds interacting with HsPDF in a primary screen using the quick and robust FP assay. This will allow us to apply the more time-consuming assay based on PDF enzymatic activity only to a vastly reduced number of compounds, in order to confirm the hits. Another advantage in using this combination of two assays lies in its reliability. A screen based on two different techniques is likely to lead to the identification of trustable hits. Indeed, the likelihood that a compound interferes with both assays, and therefore behaves as a false positive in both assays, is vastly reduced compared to a strategy solely based on one technique.